Absorbent for gases



A cLAUDE P. McNEIL, or NEW YORK,

1,441,696 PATENT OFFICE.

N. Y., AND EUGENE P. BROWN, OF WRITING,

INDIANA.

, ABSORBE1\TT FOR GASES.

'No Drawing. Application filed May 2,

7 To all whom it may concern:

Be it known that we, CLAUDE P. MQNEIL and EUGENE P. BRowN, citizens of the United States, and residing at New York, N. Y., and Whiting, Indiana, respectively, have invented .certain new and useful Improvements in Absorbents for Gases, of which the following is a specification.

This inventio relates to absorbents for gases of the well-known sodalime type. Such absorbents have proven rather unsatisfactor by reason of a lack of hardness and durability under ,various conditions,l To overcome this difiiculty, it has been attempted to incorporate Portland cement into the mixture, but an absorbent containing such cement has been found to be relatively soft, has an inferior activity towards the absorption of gases, is not porous, and the cement constitutes a dead'weight within the ab-- sorbent.

The present invention contemplates the omission of cement and obviates the dis-' advantages of prior mixtures, it being among the objects. of this invention to produce an absorbent which is hard, porous, permanent, non-deliquescent, having high activity and .capacity, preferably alkahne, and capable of use as an absorbent for gases or vapors; In carrying the objects ofthis invention into effect, we provide a composition having properties peculiarly adapting the material to eflicient absorption of' poisonous and other gases or vapors.

Specific examples of poisonous and noxious gases or vapors for which these absorbents have been found suitable are chlorinated organic compounds, such as chlorpicrin and phosgene; reducing compounds,

such as arsine; acid compounds, such as hyldrochloric acid; and certain more or less stable compounds, such as water vapor, CO gas and some hydrocarbon vapors. The absorbent is specially fitted for purifying air to be breathed by men or other animals and if usedin canisters in connection with gas masks will afford protection against certain toxic war gases, examples of which have'been heretofore enumerated. Another use for this absorbent is in the recovery of vapors or liquids of low boiling point, such as the low boiling hydrocarbons, which are otherwise lost in'the industries.

Our absorbent may be varied considerably in compositio 'but usually includes alkaline 919. Serial. No. 294,355.

material such as hydrated lime, magnesia,

sodium hydroxide or potassium hydroxide or mixtures of two or more of these. For porosity, we use aluminous or silicious material. such as kieselguhr, diatomaceous earth, infusorial earth, silicious sinter, pumice or volcanic dust; Finely divided active absorbent carbon is generally added on account of its high efficiency in the adsorption of gases and the porosity which it lends to the completed absorbent.

The activated absorbent carbon may be produced by heating carbon, such as coal, charcoal, etc., in the presence of mild oxidizing agents such as air, steam, G0,, etc., at temperatures above 700 C. for'several hours, If air is used as the oxidizing agent, lower temperatures may be employed and the heating is continued for a shorter time than when steam or CO is employed. After heating, the activated carbon isthen ground and is ready for incorporation with the.

sorbent; by the crystallization of onev or more constituents which causes hardening due to the interlocking of crystals which develop within the material; or by the forma-- tion of silicates, aluminates or alumina-silicates or similar substances, which takes place when material containing acidic and basic components as above mentioned are mixed. These substances not only render" the absorbent harder but tend to increase the activity.

A process of preparation of the absorbent which we have found to give good results is as follows: The dry materials are thoroughly mixed in the dry state and are charged along with the soluble materials in solution into a mixer of any well known type and mixing is continued until the wet mixture is uniform in composition. The mixture is immediately dumped on trays where it. is spread out to anapproximately uniform thickness. The trays have heavy iron wire cloth bottoms of large mesh so that the elimination of water in setting takes place from the lower as well asthe upper surface. After slabbing, the trays are placed in open rooms which are kept at normal temperature until initial hardness sets in, which occurs in one to ten days, usually inabout two days. The drying of the cake to the desired moisture content is carried out under vacuum or under atmos heric pressure at temperatures less than 1 5 C. until the moisture content is between 3 and 20%.

Alkaline earth hydrate, such as hydrated lime 10 to 87 Caustic alkali, such as caustic soda- 0 to. 6

Per cent.

silicious material, such as kieselguhr 5 to 25 Active absorbent carbon Oto 75 Moisture 3 to 20 We may omit one or more of the constituents, but preferably we use the combination of materials above set forth. It is desirable that some easily soluble form of silica such as occurs in amorphous form, e. g., kieselguhr, diatomaceous earth, pumice or volcanic dust or finely divided silicious sinter and some soluble form of alumina such as precipitated aluminum hydroxide or hydrated alumina be present so that the system may be provided with these components which have an important bearing on the development of the hardness of the finished product.

We do not intend to limit ourselves to the specific combination of materials described nor to the exact proportions of the constituents of our absorbent, except as limited by the following claims:

We claim as our invention: i

1. A hard, porous, non-deliquescent absorbent having high activity and capacity comprising the reaction products of basic material, silicious material and activated carbon.

2. A hard, porous, non-deliquescent absorbent having high activity and capacity comprising the reaction products of alkaline earth hydrate, caustic alkali silicious sorbent having high activity and capacity and an alkaline reaction comprising the reaction'products of alkaline earth hydrate, caustic alkali, silicious material and activated carbon.

6'. A hard, porous, non-deliquescent absorbent having high activity and capacity and an alkaline reaction comprising the re action products of hydrated lime, caustic soda, kieselguhr andactivated carbon.

7. A hard, porous, non-deliquescent absorbent having high activity and capacity comprising the reaction products of alumino-silicate and activated carbon.

8. A hard, porous, non-deliquescent absorbent having high activity and capacity and an alkaline reaction comprising the reaction products of alumino-silicate and ac tivated carbon.

9. A hard, porous, non-deliquescent, absorbent having high activity and capacity comprising the reaction products of alkaline earth hydrate, caustic alkali, silicious material, activated carbon and moisture, in the proportions described.

' CLAUDE P. MoNEIL.

EUGENE P. BROWN. 

